Expect 25°C daytime maximum temperatures in the shade with on average 10 hours of sunshine per day in Idaho in September. Check more long-term weather averages for Idaho in September before you book your next holiday to Idaho in 2018. The September weather averages shown above are for Boise.

Guide to Idaho weather in September

The average maximum daytime temperature in Idaho in September is a warm 25°C (77°F). The average night-time temperature is usually a cool 8°C (46°F). There are usually 10 hours of bright sunshine each day, which represents 80% of the 12 hours of daylight.

Expect 19mm (0.7 inches) of rainfall across the whole of September with 4 days with some rain falling. Maximum UV levels will be high (6 UV index) at midday when the skies are clear.

Idaho sunrise & sunset times for September 2018

Browse the sunrise & sunset times for Idaho in September 2018. Select a month to view Idaho sunrise & sunset times for the next twelve months. The Idaho sunrise & sunset times shown below are for Boise.